Despite all the ground covered by the Hutton inquiry, one question remains curiously hidden. What exactly was the role of the US Central Intelligence Agency in compiling the September 2002 dossier that helped to keep Britain on a path towards war with Iraq?
The dossier was the work of the UK's Joint Intelligence Committee, which comprises, according to Tony Blair's introduction, "the heads of the UK's three intelligence and security agencies (MI6, MI5 and GCHQ), the chief of defence intelligence, and senior officials from key government departments".
No mention there of the CIA's London station chief. Traditionally occupied by a senior American spook in his sunset years, the post of running the CIA's large London operation based in Grosvenor Square demands great skills of diplomacy rather than the stealthy ingenuity of the agency's more front-line postings such as Cairo or Moscow. And according to my CIA contacts, ever since the Second World War, the London chief and his staff have not only been on hand to consult their British counterparts but also serve on some of Whitehall's key intelligence committees.
"The JIC meetings are usually in two parts, with the 'domestic' side coming second. Our man traditionally stands up and leaves when the meeting turns to UK material," said an old hand from the CIA headquarters in Langley, Virginia. He stressed the CIA was there only to offer advice and co-operation, not with any kind of veto or vote.
I first started looking into the CIA's membership of Whitehall committees some time ago when I came across a civil servant who, asked to serve on a JIC working party, was intrigued to find that his fellow members included a burly and genial man from the CIA. This man suggested revisions to the draft report on an urgent intelligence question - "albeit in a friendly way".
Whitehall officials were adamant that there was no such American representation at the JIC. Only later, when I spoke to a few CIA people, did it become clear that my source had been telling the truth. One former US intelligence man described the London station chief's weekly attendance at the Cabinet Office meeting as a "highlight of the job". He said: "I remember the official red folder the chief used to carry to each and every meeting."
So has Blair at some point quietly removed the CIA from the JIC? Or did the CIA play a role in preparing the intelligence - which we must assume went well beyond what was in the September dossier itself - that persuaded Blair to stay on track for war? And, if so, did it suggest corrections or improvements to the dossier? This is not a matter upon which anyone will comment officially.
General Wesley Clark, when he was the supreme allied commander of Nato, once told me that intelligence was "the gold bullion of the modern state". And we get rich access to America's gold bullion in return for preserving the special relationship. All this has much more to do with why we went to war in Iraq than with the number of bottles of sarin still in Baghdad.
The nature of Britain's discussions with the US about the Iraqi threat would be a far more fruitful area for judicial inquiry than the contents of Andrew Gilligan's palmtop computer.
The author is a former editor of the Sunday Times Insight team.